export function loadStyle(url, key) {
	let keys = [];
	return new Promise((resolve, reject) => {
		if (keys.includes(key)) {
			resolve();
			return;
		}
		let link = document.createElement('link');
		link.rel = 'stylesheet';
		link.type = 'text/css';
		link.href = url;
		keys.push(key);
		resolve();
		document.head.appendChild(link);
	});
}
